Hammer strut locking pin?

Hello! So, I can't seem to figure out what this part does. It's part #82 for the USP series (all of them, I believe; I only own two). I noticed some annoying rattling in my regular USP45, figured it was something in the hammer spring region, and witnessed that pin sliding out when I removed part #132. So, I removed the pin to see if that was the cause and sure enough, it was. No more annoying rattle and the gun functions perfectly as far as I can tell. Because this had made me curious, I removed that same assembly on my USP tactical, which has not been open before today, and carefully watched as that part didn't fall out. It appears it is nonexistent in that model for me. Anyway, my question is, does this part actually... do anything important? As I said, my USP45 functioned perfectly without it, and apparently my tactical has functioned since I purchased it without it. If it's important somehow, I suppose I could reinstall it, but that rattling it caused was really annoying. Thanks in advance for any information!